This invention relates to methods of testing internal combustion engines and more particularly to methods of testing engines during the engine assembly process to detect engine defects.
In the assembly of a modern day motor vehicle including an internal combustion engine, it is imperative that the engine be quickly and efficiently tested during the assembly of the engine but prior to installation of the engine in the motor vehicle so as to identify and correct engine defects prior to installation of the engine in the vehicle.
Various apparatuses and methodologies have been proposed to perform such engine testing including, for example, a procedure whereby the engine crankshaft is rotated, various pressure and vacuum readings are taken at the intake and/or exhaust ports during the cranking operation, and the pressure/vacuum readings are evaluated in an effort to identify problems or defects in the assembled engine as indicated by abnormalities in the pressure and/or vacuum readings.
Whereas the testing method involving evaluation of noted exhaust and intake port pressures and vacuum signals is generally satisfactory, the relatively weak nature of the port signals makes them difficult to analyze with the result that major defects may be incorrectly analyzed and minor defects may be totally missed.